The present invention relates to a gluing palette for use with machines in an arrangement intended for gluing labels to objects, such as bottles or the like, said palette being intended to coact with a rotating gluing roller such as to be coated with glue and thereafter to transfer glue to a label which is transported by the palette from a label magazine to a label transfer means which is intended to transfer the glued label from the palette and to press the label onto the object or article concerned. The invention also relates to a glue transfer part intended for coaction with one such palette.
Devices of the aforedescribed kind are used, among other things, to apply labels to bottles in breweries, softdrink bottling plants and like plants, which require the labelling devices to operate at high speed. The majority of these devices include a rubber gluing roller, aluminium gluing palettes and an adjustable glue scraper which is operative in determining the thickness of the glue on the gluing roller.
These known devices must be produced with extreme accuracy and any subsequent adjustments to the devices in operation must be effected very precisely, since, for instance, the gluing palettes may only partially penetrate the glue layer on the gluing roller without making contact with the outer surface of the roller itself, since such contact would force the glue layer carried by the roller out onto the edges of the palette. This would cause glue to splash or squirt onto the palette surroundings, and would also result in glue fastening to the front side of the labels, causing the labels to be drawn-off the bottles. Loose labels which fasten to the gluing roller are difficult to remove and may result in damage to the roller, particularly when using foil labels, since such labels can cause wear on the roller when fastening between the glue scraper and the roller. A certain amount of wear can also be caused when the operator scrapes away labels that have fastened to the gluing roller with the aid of a sharp tool.
These and other problems are solved by means of the invention described in my Swedish Patent Application No. 9103026-2. According to this invention, there is used a modified form of gluing roller which permits the palettes to make contact with the outer surface of the roller, therewith avoiding the necessity of extremely narrow tolerances required by the known devices, with which the palette may only partially penetrate the actual glue layer itself without contact with the roller surface. To this end, the outer cylindrical surface of the gluing roller is provided with grooves that are filled with glue. Consequently, even if the gluing palettes make physical contact with the surface of the roller, they will not force-out glue which is liable to penetrate onto the side edges of the palettes. In order to ensure that the palettes will come into contact with the glue present in the grooves, at least the surface layers of the palettes which coact with the gluing roller are made of a slightly elastic or resilient material which will enable parts of said outer layer to be pressed into the grooves. The ridges that extend between the grooves in the gluing roller, are kept clean from glue with the aid of a glue-scraper coacting with said ridges.
Gluing palettes are normally made of aluminium, which is molded to the desired shape, and comprise a mount and a glue-transfer surface connecting with the mount. The shape or configuration of the glue-transfer surface shall correspond to the label to be coated with glue, which requires the aluminium palette to be machined or otherwise worked. The glue-transfer surface shall be slightly cupped in one direction, similar to a part of the cylindrical surface of a cylinder, so as to be able to roll on the rubber surface of the rotating gluing roller, and must therefore be machined to precise tolerances.
With the intention of reducing wear on the rubber surface of the gluing roller, among other things when using metal foil labels, there have earlier been used planar steel rollers and rubber pads which have been firmly vulcanized to the aluminium palettes. These rubber-covered palettes, however, have not been intended to make contact with the smooth roller surface, or cannot be permitted to make such contact, but have solely been permitted to partially penetrate the glue layer on the outer surface of the roller, and consequently this arrangement has the drawbacks described in the aforegoing.
Naturally, such known gluing palettes could be used in the machine described in my aforementioned patent application. However, these palettes are relatively expensive to produce, and the use of aluminium palettes of known construction also results in other drawbacks. For instance, aluminium palettes are relatively sensitive to knocks and blows and other careless handling when washing and cleaning the palettes. When the fit between fingers in the label magazine or the label-transfer device and corresponding recesses in the palette is incorrect, the fingers and/or the palette are likely to be seriously damaged upon contact between the fingers and the hard aluminium palette. When such a palette is damaged, it is normally necessary to replace the entire palette, which is expensive. The replacement of damaged fingers is also expensive. Some known palettes are also firmly mounted on associated shafts, which means that larger and heavier units must be handled and replaced respectively. Furthermore, the curvature of the cylindrical surfaces of the palettes must be adapted precisely to the particular machine with which they shall be used and, consequently, the same palettes cannot be used as spares for machines which originate from different manufacturers, since the palette curvature may be different with different machines.
A prime object of the present invention is to provide a gluing palette with which the aforesaid drawbacks are eliminated, or at least greatly reduced, among other things.